Invisible ink is perfect for discreet forms of communication. You can convey secret messages with ease since the ink cannot be readily seen, under normal circumstances. Some of its variations can only be viewed if you heat the paper carrying the message. Others require decoding items that can make the letters visible when applied on the message.
Four Recipes of Invisible Ink

Several items can be used to form invisible ink. All of them are pretty abundant, so you should not have a problem making each type. Here are the four basic components for invisible ink recipe:

• Lemon
• Baking Soda
• Corn Starch
• Candle

Lemon-Based Invisible Ink

Lemon juice, being highly acidic, produces stains that can be seen through heating. If applied alone, it will make faint markings on paper. You can make the juice’s trail completely invisible by adding water. The more you dilute the juice, the less visible it becomes when applied on paper. You must carefully balance the amount of water that you will add or else, the juice may remain invisible even if the paper is heated.
Materials Used:

• lemon
• water
• paper
• cotton swab or toothpick
• bowl
• knife
• candle
• iodine solution (optional)

Procedure:

1. Cut the lemon in half and squeeze the contents of each half onto a bowl.
2. Add a little water to the bowl.
3. Wet a cotton swab or toothpick with the juice and test it on a piece of paper. Check if the markings that you have made are completely invisible. If not, add more water to the solution.
4. Light the candle, then put the paper a few inches above the candle’s flame. Pale tan or brown markings should appear upon heating. If the markings do not appear after a few moments, your solution is too diluted. You must add more lemon juice to make your secret message readable.
5. You can also use iodine solution to make your secret message appear. Just douse the paper with iodine. The sheet will turn blue, exposing the secret message. This option looks cooler but you may end up wasting much of the iodine solution, especially if your secret message is long.

The trick to perfecting the lemon-based invisible ink is to add small amounts of water until you get your desired results. The process may be slightly tedious, but at least, you wouldn’t be wasting lemons.

On a side note, you can use other acidic items when making invisible ink. Vinegar, wine and other citrus fruits are good substitutes if ever you do not have lemons at home.
Baking Soda-Based Invisible Ink

Baking soda works just like lemon juice, when used for creating invisible ink. You must balance the amounts of the powder and water before you get the optimum result. The same heating process is also involved when making the secret message visible. Even the color of the hidden message is somewhat similar.
Materials Used:

• baking soda
• water
• measuring cup
• bowl
• paper
• candle
• cotton swab/toothpick

Procedure:

1. Put some baking soda into a bowl then add water. Ideally, the amount of both items should be balanced. Use a measuring cup so that you can take note of the amount of each.
2. Mix the solution well.
3. Dip a cotton swab or toothpick into the solution and write down your secret message on a piece of paper. If the message is visible upon application, add more water to the solution.
4. Heat the paper using your candle. Your message should have a faint brown hue when heated. If the message does not appear, you must add a little baking soda to the solution. Keep balancing the amounts of the baking agent and water, until you get your desired results.

Baking soda-based invisible ink is a bit easier to make than its citrusy counterpart. Most homes keep a good amount of baking soda since it is a necessary ingredient for baking pastries. You can easily grab a handful of baking soda whenever you choose, compared to rummaging for extra lemons in the vegetable chiller.
Corn Starch-Based Invisible Ink

Creating corn starch-based invisible ink is similar to the previous two but the measurement of each component is more critical with this method. The manner of making the secret message appear is slightly more tedious as well. You need to create a separate solution that will bring color to your message.
Materials Used:

• 2 tbsp corn starch
• 1 cup water
• iodine
• paper
• pan
• bowl
• cotton swab/toothpick
• cotton ball
• oven

Procedure:

1. Heat the corn starch and 1 tbsp of water on a pan, until they become warm. Stir the solution thoroughly, while heating.
2. Dip a cotton swab or toothpick in the solution then write your secret message on a piece of paper. If the message is visible, add a little water to the solution.
3. Let the paper dry.
4. Put one tsp of iodine and 10 tsp of water into a bowl. You can proportionally add more of both ingredients, depending on the length and size of your message.
5. Stir the iodine solution well.
6. Dip a cotton ball in the solution and apply it on your secret message. The message will bear a purple hue, once it makes contact with iodine.

This option is slightly more complicated than the other ones. Given the lengthy process for making the message appear, the corn starch-based invisible ink is perfect for the most secret of messages.
Candle-Based Invisible Ink

The candle is your most basic form of invisible ink. Making an actual solution is not required. You just have to use the candle as your makeshift pen when creating the message. In revealing the message, a few strokes of watercolor will do.
Materials Used:

• candle
• paper
• watercolor set
• water
• glass

Procedure:

1. Get a candle and just like a pen, use it to write your message on a piece of paper. Keep the paper close to the wick, without touching the flame, so that an invisible wax trail will form.
2. Put some water in a glass.
3. Dip your paint brush into the glass then dampen your chosen color.
4. Apply the brush on the sheet of paper to reveal your secret message.

The candle comes as the easiest option among the bunch but it is also the least accurate. Just use this method when all the other options are not available.

Invisible ink provides a good way to send sensitive information over to your friends. You can relay the latest gossips and issues around the office without being noticed, if you use invisible ink. Just make sure that the fire alarm in your building isn’t triggered, when you are revealing secret messages.

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